Method of forming composite articles



May 9, 1944.

E. J. FIEKERS 2,348,287

METHOD OF FORMING COMPOSITE ARTICLES Filed March 2, 1942 INVENTOR. I EDMUND J. FIEKERS WiM ATTORN EYS' ' polymers.

Patented May 9, 1944 I UNITED STATES PATENT OFFICE METHOD'OF FORMING COMPOSITE ARTICLES Edmund J. Fiekers, Pontiac, Mich., assignor to Baldwin Rubber Company, Pontiac, Mich a corporation of Michigan Application March 2, 1942, Serial No. 433,100 1 Claim. 154-2) This invention relates to composite articles and pressure is applied, the plastic member is and to an improved method of manufacturing softened by the solvent material retained in the such articles. v absorbent material and penetrates the absorbent Heretofore considerable difliculty has been ex- 7 material to effect a strong gas tight bond around perienced in manufacturing composite articles 5 the plastic windows. where the materials required possess radically Still another object of this invention is to condiflerent characteristics and where the joint betrol the how characteristics of the solvent emtween the dissimilar materials must not only be ployed and also the pressure applied so as to gas tight but must also remain gas tight when 7 prevent displacement of the solvent or the sofsubiected to considerable stress. This problem 10 tened plastic material from the pockets.

is particularly critical in cases where, for ex- The foregoing, as well as other objects, will ample, one material is rubber or possesses charbe made more apparent as this description proacteristics similar to rubber and where the other ceeds, especially when considered in connection material is a plastic such, for example, as celwith the accompanying drawing, wherein: lulose acetate, acrylic acid ester vinyl halide Figure 1 is a front elevational view of a part or ester polymers. Materials having such radiof a gas mask embodying the present invention; cally difierent characteristics are extremely dif- Figure 2 is a longitudinal sectional view showficult to bond together and are usually Joined ing the seals around the windows for the gas by mechanical or some equivalent relatively commask; and plicated means which not only requires consider- Figure 3 is an elevational view partly broken able time in manufacture and assembly but are away and illustrating several steps in the method none too satisfactory in use. of manufacturing the gas mask.

It is one of the principal objects of this in- Although some "or all of the principles of this vention to integrally connect materials of the invention may be advantageously employed in above general type without the assistance of memanufacturing numerous diiferent types of comchanical or equivalent means by bonding one posite articles embodying materials having charmaterial to the other in a manner to provide a acteristics similar to the specific materials heregas tight seal therebetween which will withinafter described, nevertheless, I have selected stand considerable stress without breaking downa composite article in the form of a gas mask In accordance w t is invention an absorbfor the purpose of illustrating the invention; t mate i l is a p d to e s of a rubber- With this in view reference is made to the sev- Hke member and is coated with one of SO1- era] figures of the drawing wherein the refer- Vents for the particular plastic member is deence character designates generally a gas sired to secure to the rubber-like member so that mask having a body member H of t usual by pressing the plastic member against the surshape and having windows located m the face of absorbent materill, the plastic is softened by the solvent sufliciently to penetrate body member to insur? unobstructed vision th e the absorbent surface and bond the plastic mem- 3. ggg member H comprises a sheet of the rubber'nke memberflexible material i3 which is impervious to mois- The above features of this invention are es- 40 tur 1 pecially applicable to the manufacture of gas H zg ggg ii g afg f gigggg $3 35:

masks where the body part of the mask is formed I 3, it will be noted that a second sheet of mate? of a rubber like material which is impervious rial I5 is secured to the Sheet '3 in super to moisture orv gas and where the windows are formed of a plastic material such,as cellulose posed relationship to the latter sheet and is proacetate, acrylic acid esters, vinyl halide or ester vided with openings registering with the open ings I4 in the sheet i3.

In connection with the. above application of It W11] also be noted from Flgul'e 3 that the the invention, it is a further object to surround portions of the sheets and surrounding the each window opening in the body part with an 60 Openings therethrough cooperate with one anannular pocket lined with a material possessing other to form an annular pocket 1 channel H the absorbent qualities required to retain the around Bach the Openings- The pposed'walls appropriate solvent for the plastic member so of each annular pocket are lined with an that after the peripheral portions of the plastic absorbent material I! and these linings are remembers are respectively engaged in the pockets 'spectively integrally secured to the inner suropenings ll.

although cellulose acetate is specifically referred 7 faces of the walls in a manner to be more fully hereinafter described.

The windows l2 are in the form of transparent discs having a diameter greater than the diameter of the registering openings through the sheets of the body' member H and slightly less than the maximum diameter of the pockets II. This construction enables the peripheral portions of the windows I2 to extend for a substantial distance into the pockets II with the opposite sides thereof contacting the absorbent linings l9. As will be presently set forth, the opposite sides of the. peripheral portions of the windows are-integrally bonded with the linings I9 on the opposed walls l8 of the pockets in a manner to provide an effective gas tight seal around each window which will maintain its effectiveness over a long period of use and under any normal stresses to which the construction is liable to be subjected to during use or handling.

In the present instance, the windows or discs |2 are formed of a plastic material characterized in that it becomes soft in the presence of a solvent and possesses adhesive qualities. In general, any material having the above characteristics may be used and particularly satisfactory results have been obtained by using a plas tic material such, for example, as cellulose acetate, acrylic acid esters, vinyl halide or ester polymers. When using a plastic material of the above general types, various solvents may be employed. I prefer to use any solvent in the ketone class such as acetone. may be used such as ethyl acetate, butyl acetate and Cellosolve. Alcohols may be used with some types of plastics but are generally less effective than the ketones. Depending upon the choice of lastic, m'anydiiferent solvents may be used, among which may be aromatic hydrocarbons, chlorinated hydrocarbons, hydrogenated hydrocarbons, etc.

In manufacturing the composite article, I prefer to apply the solvent to the absorbent linings 19 of the opposed walls iii of the pockets n so thatwhen the peripheral portions of the windows I2 are engaged in the pockets, a reaction takes place which softens the peripheral portions of the windows. when the peripheral portions of the windows are softened by the solvent treated linings, they become tacky and a sufficient amount of the plastic material permeates the linings, particularly if pressure is applied, to integrally join the peripheral portions of the windows with the opposed walls of the pockets. Particularly satisfactory results have been obtained by employing a solvent or softener containing approximately by weight of cellulose acetate and approximately 95% by weight of acetone. The cellulose acetate is employed to control the viscosity of the acetone and the proportion of the cellulose acetate used may vary within wide limits depending upon the degree of viscosityv desired. In the present instance, the amount of cellulose acetate in the compound is determined to enable the compound to readily permeate the absorbent linings IS without becoming so thin as to drain or escape from the pockets l1 onto the portions of the windows l2 in the It will also be understood that to, any material capable of dissolving in the solvent and increasing its viscosity may be used. For example, in the case of acetone, cellulose nitrate, polymerized vinyl halide and many natural or synthetic resins or gums may be used.

However, various esters- The sheet I3 is formed of rubber, synthetic rubber or any material which is impervious to moisture and gas and is capable of being vulcanized. Although the sheet l5 may be formed 5 of the same material as the sheet l3, nevertheless, I prefer to form this sheet from a material having more rigidity than the sheet iii. In detail, the sheet l5 comprises a fabric material calendered on both sides with a rubber material 1 which. flows into the interstices of the fabric and forms in effect a rubberized sheet capable of being cemented, vulcanized or otherwise integrally united to the sheet l3.

The linings 19 for the Opposed walls l8 of the pockets I! have the adjacent or inner surfaces formed of absorbent material such, for example, as a suitable fabric and the outer surfaces of the linings are coated with a suitable adhesive material such, for example, as rubber 2o cement. The fabric used in forming the linings is selected for its absorbing qualities and particularly satisfactory results have been obtained by using twill which is napped on one side to prevent bleeding of the rubber stock therethrough during the forming operations. The purpos of the adhesive on the twill is to enable securing the latter in place during the interval the sheet I3 is vulcanized and secured to the sheet I5.

With the above in view reference will now be made to the method of manufacture. In detail, a sheet of uncured vulcanizable material i3 is die cut or otherwise formed to the contour shown in Figure 1 and this sheet is laid flat on a form, "not shown, of a suitable vulcanizing press. A 3:; pair of discs 2| having a diameter equal to the maximum diameter of the pockets and formed of the lining material, previously described, are respectively supported on the uncured sheet l3 at the proper locations for the windows with the adhesive surfaces of the discs contacting the adjacent surface of the sheet l3. Similar discs 22 are respectively positioned on the discs 2| with the fabric or absorbent surfaces respectivelycontacting the corresponding surfaces of the discs 2|. I

After the discs are properly positioned on the uncured sheet of stock IS, a sheet I5 of the same material as the sheet is of the finished product is placed over the discs in the manner indicated in Figure 2. This subassembly is then subjected to suflicient heat to vulcanize the sheet v i5 to the sheet l3 and to also vulcanize or cement the discs 2| to the sheet I! and the discs 22 to the sheet l5. Owing to the fact that the adjacent or mating surfaces of the discs are of fabric material, it follIws that these surfaces of the discs do not adhere to one another. Upon completion of the vulcanizing operation, the subassembly is subjected to a suitable die cutting an operation to form the window openings through the subassembly. Inasmuch as the window openings are of less diameter than the discs and in view of the fact that these openings are formed through the center of the discs, it follows that an annular pocket I1 is formed around each window opening with a lining of absorbent material. Upon completion of the die cutting operation, the appropriate solvent is applied to the linings I9. The pockets are then in condition to receive the peripheral edge portions of the windows or discs l2 and the diameter of the latter is such as to enable the peripheral portions thereof to extend for a substantial distance into the pockets. Owing to the nature of the material from which 76 the discs I: are formed, the peripheral portions shape to form the sheet assess? oi the discs dissolve to some extent under the iniluence of the solvent and permeate the absorbent linings of the pockets. This action is facilitated by the application of opposing pressures to the opposite side walls of the pockets. This pressure is controlled so as not to displace either the solvent or the softened peripheral portion of the discs from the pockets. Particularly satisfactory results have been secured by using pressures of approximately twenty pounds per square inch, although this pressure is not critical and may vary considerably.

After the assembly resulting from the above is permitted to dry or set for an appropriate time period, the sheet I3 is cut to proper size and I: of the completed gas mask. In addition, the chin portion 25 of the gas mask is spliced and shaped to the contour illustrated in Figure 1.

As a result of the provided wherein the 01' both windows are foregoing, a gas mask is peripheral edge portions each of the windows. the above feature is obtained without the assistance of mechanical clamping devices or their equivalents and, therefore, the masks may be expediently manufactured and assembled. In addition, the nature of the integral Joint between the peripheral portions of the windows and the mask material to the opposed walls of a pocket or is such as to withstand considerable stress without the danger of developing a leak.

While in describing the foregoing particular stress has been placed on bonding the plastic in the body member, nevertheless; it is evident that under some conditions the pocket or channel may be omitted. In the event the pocket or channel is omitted, the absorbent material is secured to one side of the body memchannel formed her and the plastic material is bonded to the abin the same manner described above in connection with the pockets. Such an sorbent surface arrangement may be used in cases where a double seal is not essential and where the construction is not subjected to high stresses. Therefore, reservation is made to make such changes in the details of construction and method of manufacture as may come within the purview of the accompanying claim.

What I claim as my invention is:

The method of forming a composite article comprising placing two superimposed members of absorbent material between superimposed sheets of vulcanizable material, vulcanizing the sheets while holding adjacent surfaces in contact to secure the sheets together and to the adjacent surfaces of the members, forming an opening through the sheets and members to provide a pocket around the opening with absorbent linings on opposed walls thereof, applying a solvent to the linings, inserting into the pocket the outer edge portion of a closure comprising a material which is soluble in the solvent solution and becomes tacky when softened, and forcing the opposed linings into intimate contact with the adjacent portion of the closure to impregnate the linings with the softened material from the closure,

EDMUND J. FIEKERS. 

